Can you lose weight after your first work out?

My husband and I are both overweight... We eat pretty healthy but don't really exercise and our metabolisms suck. Yesterday we started bike riding and we rode for about an hour on a moderate path.  For the past year my weight has bounced around from 237 to 239 but today when I weighed myself I was 236... Im wondering if it's even possible to lose weight after a first workout? That bike ride is literally the only thing that I did differently... I'd say it was just a coincidence but I haven't been 236 since last year... I weigh myself often and lately I've been stuck at 237 so in that one day it says I lost a pound... I'm not trying to say I lost anything major lol. I know being overweight you burn calories faster... So is that 1-pound-loss because I exercised?